Method for re-direction of uplink access

ABSTRACT

A method for prompt re-direction of uplink access of a specific user equipment is disclosed. For initial random access to a network, if a user equipment transmits a preamble, which includes information related to random access, to a network node, the network node sends grant/rejection information of the preamble and re-direction information as a response message to the preamble. In comparison with the related art which controls a rush of an access request of the user equipment through a second response message from the network node, since the rush of an access request is controlled by a first response message in the present invention, it is possible to promptly deal with abnormal communication status, thereby improving communication efficiency.

TECHNICAL FIELD

The present invention relates to a method for prompt re-direction of anuplink access in a mobile communication network.

BACKGROUND ART

In a mobile communication network, a user equipment in an idle mode usesa random access channel (RACH) to transmit an initial control message toa network. In other words, the user equipment uses the RACH to adjusttime synchronization with the network or acquire a radio resource incase of no radio resource in an uplink to which data will be transmittedwhen the user equipment desires to transmit the data to the uplink.

For example, if the user equipment is powered on and then desires tofirst access a new cell, the user equipment should transmit an accessrequest message to the uplink for radio resource control connection (RRCconnection) after adjusting synchronization of a downlink and receivingsystem information of a cell which the user equipment desires to access.However, since the user equipment is not adjusted to the current networkin time synchronization and does not ensure the radio resource of theuplink, the user equipment requests a base station of a radio resourcefor transmission of a connection request message to the network throughthe RACH. The base station which has been requested the radio resourcefrom the user equipment allocates a suitable radio resource to transmitthe RRC connection request message to the corresponding user equipment.

For another example, it is assumed that the user equipment is in an RRCconnection mode as RRC connection is formed between the user equipmentand the network. In this case, the user equipment is allocated with aradio resource depending on radio resource scheduling, and transmitsuser data to the network through the corresponding radio resource.However, if data to be transmitted does not remain in a buffer of theuser equipment, the network does not allocate the radio resource to thecorresponding user equipment any more. At this time, the buffer statusof the user equipment is reported to the network either periodically orwhenever an event occurs. In this case, even though new data occurs inthe buffer of the user equipment to which the radio resource is notallocated, since there is no radio resource allocated to the userequipment, the user equipment requests the network to allocate a radioresource required for data transfer, through the RACH.

Hereinafter, an initial access procedure of the user equipment to thenetwork through the aforementioned RACH in a long term evolution (LTE)system will be described, wherein the LTE system has attracted attentionas the communication standard for next generation.

FIG. 1 is a signal flow chart illustrating an initial access procedureof the user equipment discussed in the LTE system according to therelated art.

The user equipment selects RACH signature and RACH occasion throughsystem information transmitted from the base station, and transmits theselected RACH signature and RACH occasion to the base station through arandom access preamble (S101).

After receiving the random access preamble from the user equipment, thebase station transmits a random access response to the correspondingpreamble to the user equipment (S103). The random access responseincludes timing offset information (Time Advance: TA) and information ofradio resource allocation of the uplink for transmission of the RRCconnection request message.

After receiving the random access response, the user equipment transmitsthe RRC connection request message in accordance with the information ofradio resource allocation included in the random access response (S105).

After receiving the RRC connection request message from the userequipment, the base station transmits RRC connection establishmentmessage or RRC contention resolution message to the user equipmentdepending on circumstances (S107).

In the RRC connection procedure using random access according to therelated art, if it is necessary to limit uplink access of the userequipment due to frequent transmission of the RRC connection requestmessage, a wireless network transmits RRC connection rejection message,which includes re-direction information, to allow a specific userequipment to be re-directed to another frequency band or another system.However, since the re-direction information according to the related artis transmitted through the fourth message (S107) of random access, aproblem occurs in that the wireless network fails to promptly controluplink access of the specific user equipment.

DISCLOSURE OF THE INVENTION

Accordingly, the present invention is directed to a method forre-direction of uplink access, which substantially obviates one or moreproblems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a method of promptlycontrolling uplink access of a specific user equipment, in which apreamble including random access information is transmitted to a basestation and its response message which is information required forre-direction access of the user equipment is transmitted to the userequipment.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, amethod for random access by a terminal in mobile communication systemincludes transmitting a random access preamble to a network, andreceiving from the network a response message corresponding to therandom access preamble, wherein if the response message comprisesnegative control information, the response message comprises additionalcontrol information.

In another aspect of the present invention, a method for controllingrandom access by a network in mobile communication system includesreceiving a random access preamble from least one terminal, andtransmitting to the at least one terminal a response messagecorresponding to the random access preamble, wherein if the responsemessage comprises negative control information, the response messagecomprises additional control information.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a signal flow chart illustrating an initial access procedureof a user equipment discussed in LTE system according to the relatedart;

FIG. 2 illustrates a network structure of E-UMTS which is a mobilecommunication system to which the present invention is applied;

FIG. 3 and FIG. 4 illustrate a structure of a radio interface protocolbetween a user equipment and UTRAN based on 3GPP radio access networkstandard;

FIG. 5 is a signal flow chart illustrating an initial random accessprocedure of an idle user equipment according to the present invention;

FIG. 6 is a signal flow chart illustrating an initial random accessprocedure of RCC connection user equipment according to the presentinvention; and

FIG. 7 illustrates an example of HARQ which is applied to a downlinkphysical layer of a radio packet communication system.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the preferred embodiment of the present invention will bedescribed with reference to the accompanying drawings, examples of whichare based on the background of the present invention.

FIG. 2 illustrates a network structure of Evolved Universal MobileTelecommunications system (E-UMTS) which is a mobile communicationsystem to which the present invention is applied.

The E-UMTS is a system evolving from the conventional UMTS and its basicstandardization is currently handled by the 3GPP (3^(rd) GenerationPartnership Project). The E-UMTS can also be called an LTE (Long TermEvolution) system.

The E-UMTS can be classified into E-UTRAN 100 and CN 200.

The E-UTRAN 100 includes an access gateway 110 (hereinafter, referred toas ‘AG’) connected to an external network by being located at an end ofthe E-UMTS network, a network node 120 (hereinafter, referred to as‘eNode B’), and a user equipment (hereinafter, referred to as ‘UE’). TheAG 100 may be classified into a part for handling user traffic and apart for handling control traffic. In this case, a new interface may bedefined between AG for processing new user traffic and AG for processingcontrol traffic to perform communication between them. One eNode B 120may include at least one cell. An interface for transmitting usertraffic or control traffic may be located between several eNode Bs.

The CN 200 may include the AG and a plurality of nodes for registeringusers of UE 130. If required, another interface for discriminatingbetween the E-UTRAN 100 and the CN 200 may also be used for the LTEnetwork.

Radio interface protocol layers between the UE 130 and the network canbe classified into a first layer L1, a second layer L2, and a thirdlayer L3 based on three lower layers of an open system interconnection(OSI) reference model which is widely known in a communication system. Aphysical layer corresponding to the first layer provides informationtransfer service using a physical channel, and a radio resource control(hereinafter, referred to as ‘RRC’) layer located in the third layerserves to control radio resources between the user equipment and thenetwork. To this end, the RRC layer exchanges RRC messages between theuser equipment and the network. The RRC layer may be located by beingdistributed in respective nodes of the network such as the eNode B 120and the AG 110. Alternatively, the RRC layer may be located only in theeNode B 120 or the AG 110.

FIG. 3 and FIG. 4 illustrate a structure of a radio interface protocolbetween the user equipment and UTRAN based on the 3GPP radio accessnetwork standard.

The radio interface protocol between the user equipment the UTRANhorizontally includes a physical layer, a data link layer, and a networklayer. The radio interface protocol between the user equipment and theUTRAN vertically includes a control plane (FIG. 3) for signaling of acontrol signal and a user plane (FIG. 4) for transmission of datainformation. The protocol layers of FIG. 3 and FIG. 4 can be classifiedinto a first layer L1, a second layer L2, and a third layer L3 based onthe three lower layers of the OSI reference model which is widely knownin the communication system.

The respective layers of a radio protocol control plane shown in FIG. 3and a radio protocol user plane shown in FIG. 4 will be described indetail.

First of all, the physical layer 10 which is the first layer providesinformation transfer service to an upper layer using physical channels.The physical layer 10 is connected to a medium access control(hereinafter, referred to as ‘MAC’) layer 20 above the physical layer 10via transport channels. Data are transferred between the medium accesscontrol layer 20 and the physical layer 10 via the transport channels.Moreover, data is transferred between different physical layers, andmore particularly, between one physical layer of a transmitting side andthe other physical layer of a receiving side via the physical channels.

The medium access control (hereinafter, referred to as ‘MAC’) layer 20of the second layer provides a service to a radio link control layerabove the MAC layer via logical channels. A radio link control (RLC)layer 30 of the second layer supports reliable data transfer. Meanwhile,the RLC layer 30 may be realized by functional blocks inside the MAC. Inthis case, the RLC layer may not exist. In order to effectively transmitIP packets (e.g., IPv4 or IPv6) within a radio-communication periodhaving a narrow bandwidth, a PDCP layer 50 of the second layer performsheader compression to reduce the size of a relatively-large IP packetheader containing unnecessary control information.

A radio resource control (hereinafter, referred to as ‘RRC’) layer 40located on a lowest part of the third layer is defined in the controlplane only and is associated with configuration, reconfiguration andrelease of radio bearers (hereinafter, referred to as ‘RBs’) to be incharge of controlling the logical, transport and physical channels. Inthis case, the RB means a service provided by the second layer for thedata transfer between the UE and the UTRAN.

As a downlink transport channel carrying data from the network to UEs,there are provided a broadcast channel (BCH) carrying system informationand a downlink shared channel (SCH) carrying user traffic or controlmessages. The traffic or control messages of a downlink multicast orbroadcast service can be transmitted via the downlink SCH or anadditional downlink multicast channel (MCH). Meanwhile, as an uplinktransport channel carrying data from the UEs to the network, there areprovided a random access channel (RACH) carrying an initial controlmessage and an uplink shared channel (UL-SCH) carrying user traffic orcontrol message.

Next, a procedure of transmitting the initial control message from UEwhich is in an idle mode to the network will be described in detail.

In a wideband code division multiple access (WCDMA), the RACH is used toupwardly transmit control message or data of short length. Some of RRCmessages, such as RRC connection request message, cell update message,and URA update message, are transmitted through the RACH. Also, amongthe logical channels, a common control channel (CCCH), a dedicatedcontrol channel (DCCH), and a dedicated traffic channel (DTCH) can bemapped with the RACH of the transport channel. The RACH of the transportchannel is again mapped with a physical random access channel (PRACH).

If the MAC layer of the UE commands the physical layer of the UE toperform PRACH transmission, the physical layer of the UE selects oneaccess slot and one signature to upwardly transmit a PRACH preamble. Thepreamble is transmitted for an access slot period of length of 1.33 ms,and one signature among 16 signatures is selected and transmitted for afirst certain length of the access slot.

If the UE transmits the preamble, the network node transmits a responsesignal through an acquisition indicator channel (AICH) which is adownlink physical channel. The AICH transmitted in response to thepreamble transmits the signature selected by the preamble for a firstcertain time period of an access slot corresponding to the access slotto which the preamble is transmitted. At this time, the network nodetransmits acknowledgement (ACK) or negative-acknowledgement (NACK)through the signature transmitted from the AICH. If the UE receives ACK,the UE transmits a message part of 10 ms or 20 ms by using an orthogonalvariable spreading factor (OVSF) code corresponding to the transmittedsignature. If the UE receives NACK, the MAC of the UE again commands thephysical layer of the UE to perform the PRACH transmission after aproper time period. Meanwhile, if the UE does not receive the AICHcorresponding to the transmitted preamble, the UE transmits a newpreamble at a power higher than that of the previous preamble by onelevel after a given access slot.

Hereinafter, the initial random access procedure according to thepresent invention will be described in detail.

EMBODIMENT 1

FIG. 5 is a signal flow chart illustrating an initial random accessprocedure of an idle user equipment according to the present invention.

First of all, the UE transmits a random access preamble to the networknode (S201). At this time, the UE can include uplink message informationor channel measurement information in the preamble along with thesignature so that the network node can perform resource allocation foruplink transmission.

The network node responds to the preamble as the random access responseinformation (S203). At this time, the response information messageincludes at least one of the signature transmitted from the UE and grantor rejection information of the signature transmission. The responseinformation message further includes temporary cell radio networktemporary identifier (Temporary C-RNTI) allocated to the UE, radioresource allocation information of the RRC connection request message,message size, radio parameters (modulation and coding information andhybrid ARQ information) for RRC connection request message transmission.

Transmission information of the response information message is reportedthrough L1/L2 control channel related to the response informationmessage transmission. The L1/L2 control channel includes RA-RNTIindicating transmission of the response information and transmissionparameters related to the corresponding response information messagetransmission.

Also, the response information message may further include re-directioninformation, wait time, and reject cause.

After receiving the response information message, if the signaturetransmitted from the UE is included in the response information messageand if there is grant for signature transmission, the UE transmits theRRC connection request message to the network node (S205). At this time,the UE transmits the RRC connection request message by using the radioresource allocation information, the message size, and the radioparameters, which are included in the response information message. TheRRC connection request message may include a wideband UE identifier suchas international mobile subscriber identity (IMSI) or temporary mobilesubscriber identity (TMSI).

If the signature transmitted from the UE is included in the responseinformation message but there is rejection with respect to signaturetransmission, or if the signature transmitted from the UE is notincluded in the response information message, the UE retransmits thepreamble after a wait time designated in the response informationmessage or a certain time period without transmitting the RRC connectionrequest message.

Selectively, if the response information includes rejection informationof the preamble, the UE may retransmit the preamble depending on thewait time previously established in the UE to request the RRC connectionregardless of whether the wait time is included in the responseinformation. Alternatively, if the response information includesrejection information of the preamble, the UE may retransmit thepreamble by applying different wait time periods depending on the numberof signatures or the number of users included in the responseinformation, message size of the response information, or the rejectcause, regardless of whether the wait time is included in the responseinformation.

At this time, if re-direction information is included in the responseinformation message, the UE transfers to another system or anotherfrequency band depending on the re-direction information to select acell again and retry random access.

If the RRC connection request message is received from the network node,the RRC layer of the network node transmits the RRC connectionestablishment message or the RRC contention resolution message to the UE(S207).

If a plurality of UEs upwardly transmit preambles at the same time byusing the radio resource such as the signature, contention occursbetween respective transmissions. Accordingly, the network nodetransmits the RRC contention resolution message to each of the UEs toresolve the contention status. The RRC contention resolution message.includes radio network UE identifier such as C-RNTI, the wideband UEidentifier, and re-direction information. The RRC contention resolutionmessage may further include wait time and reject cause.

Therefore, if the RRC contention resolution message includes thewideband UE identifier sent through the RRC connection request message,the UE recognizes that it gets out of the contention. However, if the UEdoes not receive the RRC connection establishment message for a certaintime period, wherein the RRC connection establishment message includesthe wideband UE identifier sent through the RRC connection requestmessage, the UE retransmits the preamble after the wait time or acertain time period.

If the RRC contention resolution message does not include the widebandUE identifier sent through the RRC connection request message, the UErecognizes that it fails to get out of the contention, and retransmitsthe preamble after the wait time or the certain time period.

Preferably, if the RRC contention resolution message does not includethe wideband UE identifier sent through the RRC connection requestmessage, the UE retransmits the preamble depending on the wait timeestablished for RRC connection request, regardless of whether wait timeis included in the RRC contention resolution message. Alternatively, ifthe RRC contention resolution message does not include the wideband UEidentifier sent through the RRC connection request message, the UE mayretransmits the preamble by using different wait time periods dependingon the RRC contention resolution message (for example, reject cause),regardless of whether wait time is included in the RRC contentionresolution message.

At this time, if the re-direction information is included in theresponse information message, the UE transfers to another system oranother frequency band depending on the re-direction information toselect a cell again and retry random access.

In this case, the L1/L2 control channel which indicates the RRCcontention resolution message includes the cell radio network temporaryidentifier (C-RNTI). Accordingly, if the C-RNTI is only included in theL1/L2 control channel, the UE receives the RRC contention resolutionmessage.

EMBODIMENT 2

Next, the initial random access procedure of an RRC connection UE willbe described in detail. FIG. 6 is a signal flow chart illustrating theinitial random access procedure of the RRC connection UE.

First of all, the UE transmits a random access preamble to the networknode (S301). At this time, the UE can include uplink message informationor channel measurement information in the preamble along with thesignature so that the network node can perform resource allocation foruplink transmission.

The network node responds to the preamble as the random access responseinformation (S303). At this time, the response information messageincludes the signature transmitted from the UE and grant or rejectioninformation of the signature transmission. The response informationmessage further includes temporary cell radio network temporaryidentifier (Temporary C-RNTI) allocated to the UE, radio resourceallocation information of MAC scheduling request message, message size,radio parameters (modulation and coding information and hybrid ARQinformation) for MAC scheduling request message transmission.Transmission information of the response information message is reportedthrough L1/L2 control channel related to the response informationmessage transmission. The L1/L2 control channel includes RA-RNTIindicating transmission of the response information and transmissionparameters related to the corresponding response information messagetransmission.

Preferably, the response information message includes re-directioninformation. The response information message may further include waittime and reject cause.

After receiving the response information message, the UE transmits theMAC scheduling request message (or MAC resource request message) to thenetwork node if the signature transmitted from the UE is included in theinformation message and if there is grant for signature transmission(S305). At this time, the UE transmits the MAC scheduling requestmessage by using the radio resource allocation information, the messagesize, and the radio parameters, which are included in the responseinformation message. Preferably, the MAC scheduling request messageincludes a radio network UE identifier such as C-RNTI.

If the signature transmitted from the UE is included in the responseinformation message but there is rejection with respect to signaturetransmission, or if the signature transmitted from the UE is notincluded in the response information message, the UE retransmits thepreamble after a wait time designated in the response informationmessage or a certain time period without transmitting the MAC schedulingrequest message.

Preferably, if the response information includes rejection informationof the preamble, the UE may retransmit the preamble depending on thewait time established for MAC scheduling request regardless of whetherthe wait time is included in the response information. Alternatively, ifthe response information includes rejection information of the preamble,the UE may retransmit the preamble by using different wait time periodsdepending on the number of signatures or the number of users included inthe response information, message size of the response information, orthe reject cause, regardless of whether the wait time is included in theresponse information.

At this time, if re-direction information is included in the responseinformation message, the UE transfers to another system or anotherfrequency band depending on the re-direction information to select acell again and retry random access.

If the MAC scheduling request message is received in the network node,the MAC layer of the network node transmits a resource grant message toor MAC contention resolution message to the UE (S307).

If a plurality of UEs upwardly transmit preambles at the same time byusing the radio resource such as the signature, contention occursbetween respective transmissions. Accordingly, the network nodetransmits the MAC contention resolution message to each of the UEs toresolve the contention status. The MAC contention resolution messageincludes radio network UE identifier such as C-RNTI, the radio networktemporary UE identifier, the wideband UE identifier, and re-directioninformation. The MAC contention resolution message may further includewait time and reject cause.

If the MAC contention resolution message includes the radio network UEidentifier corresponding to the UE, the UE recognizes that it gets outof the contention. However, if the UE does not receive the resourceallocation message, which includes the radio network UE identifiercorresponding to the UE, for a certain time period, the UE retransmitsthe preamble after the wait time or a certain time period.

If the MAC contention resolution message does not include the radionetwork UE identifier corresponding to the UE, the UE recognizes that itfails to get out of the contention, and retransmits the preamble afterthe wait time or the certain time period.

Preferably, if the MAC contention resolution message does not includethe radio network UE identifier corresponding to the UE, the UEretransmits the preamble depending on the wait time established for RRCconnection request, regardless of whether the wait time is included inthe MAC contention resolution message. Alternatively, if the MACcontention resolution message does not include the radio network UEidentifier corresponding to the UE, the UE may retransmits the preambleby using different wait time periods depending on the MAC contentionresolution message (for example, reject cause), regardless of whetherthe wait time is included in the MAC contention resolution message.

At this time, if the re-direction information is included in theresponse information message, the UE transfers to another system oranother frequency band depending on the re-direction information toselect a cell again and retry random access.

In this case, if the MAC contention resolution message is transmitted toMAC control PDU, the L1/L2 control channel which indicates the MACcontention resolution message includes the radio network temporary UEidentifier. Accordingly, if the radio network temporary UE identifier isonly included in the L1/L2 control channel, the UE receives the MACcontention resolution message.

Meanwhile, a value of ‘wait time’ included in every message of thepresent invention could be an actual time or a parameter value forcalculating the wait time. If the value of ‘wait time’ is an actualtime, the UE applies wait depending on the value. If the value of ‘waittime’ is the parameter value for calculating the wait time, the UEcalculates the wait time actually applied by using the value of ‘waittime’ included in the message depending on a designated formula. In thiscase, preamble retransmission by application of different wait times isidentical with preamble retransmission by application of differentparameter values.

In the step S207 of FIG. 5 and the step S307 of FIG. 6, a hybridautomatic repeat request (HARQ) mechanism of the WCDMA can be used. FIG.7 illustrates an example of HARQ which is applied to a downlink physicallayer of a radio packet communication system.

In FIG. 7, the network node determines a user equipment which willreceive a packet and types (coding rate, modulation mode, data capacity,etc.) of the packet which will be transmitted to the user equipment,notifies such information to the corresponding user equipment throughhigh speed downlink shared control channel (HS-SCCH) transmission, andtransmits a corresponding data packet through a high speed downlinkshared channel (HS-DSCH) at this time. The corresponding user equipmentidentifies a transmission format of a packet to be transmitted to itselfand a transmission timing point by receiving a downlink control channeland receives a corresponding packet. After receiving the packet, theuser equipment performs decoding of the packet data. If the userequipment successfully decodes the packet data, the user equipmenttransmits ACK signal to the network node. The network node which hasreceived the ACK signal senses that packet transmission to the userequipment has been successfully performed and performs the next packettransmission. If the user equipment fails to decode the packet data, theuser equipment transmits NACK signal to the network node. The networknode which has received the NACK signal senses that packet transmissionto the corresponding user equipment has been failed and timelyretransmits the same data in the same packet type or a new packet type.At this time, the user equipment combines the retransmission packet withthe previous packet whose decoding has been failed in various methods toperform decoding again.

It will be apparent to those skilled in the art that the presentinvention can be embodied in other specific forms without departing fromthe spirit and essential characteristics of the invention. Thus, theabove embodiments are to be considered in all respects as illustrativeand not restrictive. The scope of the invention should be determined byreasonable interpretation of the appended claims and all change whichcomes within the equivalent scope of the invention are included-in thescope of the invention.

INDUSTRIAL APPLICABILITY

According to the present invention, the random access relatedinformation is included in the preamble and then transmitted to thenetwork node, and information required for re-direction access of theuser equipment is transmitted to the user equipment in response to thepreamble, so as to promptly control uplink access of the specific userequipment, whereby the communication system is desirably operated.

1. A method for random access by a terminal in mobile communicationsystem, the method comprising: transmitting a first random accesspreamble to a network; receiving from the network a random accessresponse message comprising wait time information; and retransmitting asecond random access preamble to the network after certain amount oftime that is based on the wait time information. 2-6. (canceled)
 7. Themethod according to claim 1, wherein the first random access preamblecomprises a signature for distinguishing the terminal from any otherterminal.
 8. The method according to claim 7, wherein retransmitting thesecond random access preamble is performed if the random access responsemessage does not comprise a signature same to the signature of the firstrandom access preamble, or if the terminal does not receive the randomaccess response message comprising the signature same to the signatureof the first random access preamble for a predetermined period. 9.(canceled)
 10. The method to claim 1 wherein the wait time informationhas a parameter value to be used in calculating an actual wait time tobe applied at determining the certain amount of time.
 11. The methodaccording to claim 1, if at least one of the first and the second randomaccess preambles is collided with other random access preamble from anyother terminal using same signature, same radio resource, and same timeas at least one of the first and the second random access preambles, themethod further comprises: receiving a contention resolution message fromthe network.
 12. The method according to claim 11, wherein if thecontention resolution message comprises a terminal identifiertransmitted by the terminal in advance, the terminal establishes anuplink access with the network; and if the contention resolution messagedoes not comprise the terminal identifier, the method further comprisesretransmitting a third random access preamble.
 13. A method forcontrolling a random access from at least one terminal by a network inmobile communication system, the method comprising: receiving a randomaccess preamble from the at least one terminal; and transmitting to theat least one terminal a random access response message comprising waittime information, wherein the wait time information is used for the atleast one terminal to determine a retransmission timing of the randomaccess preamble. 14-17. (canceled)
 18. The method according to claim 13,wherein the random access preamble comprises a signature fordistinguishing the at least one terminal from any other terminal. 19.The method according to claim 18, wherein the retransmission of therandom access preamble is performed by the at least one terminal if therandom access response message does not comprise a signature same to thesignature of the random access preamble, or if the at least one terminaldoes not receive the random access response message comprising thesignature same to the signature of the random access preamble for apredetermined period.
 20. The method according to claim 13, wherein therandom access response message is transmitted associated with a RA-RNTI(Random Access-Radio Network Temporary Identifier).
 21. The methodaccording to claim 20, wherein the RA-RNTI is transmitted through aL1/L2 control channel.
 22. The method according to claim 13, wherein therandom access response message comprising the wait time information is anegative response to the random access preamble.
 23. The methodaccording to claim 1, wherein the random access response message isidentified by a RA-RNTI (Random Access-Radio Network TemporaryIdentifier).
 24. The method according to claim 23, wherein the RA-RNTIis received through a L1/L2 control channel.
 25. The method according toclaim 1, wherein the random access response message comprising the waittime information is a negative response to the first random accesspreamble.